Abstract
Photocatalytic reduction of CO(2) to value-added chemicals is a promising technology for reducing atmospheric CO(2), but selectively producing a specific product still remains a great challenge. In this study, a Z-scheme heterojunction, N-doped HTiNbO(5)/NH(2)-UiO-66(Zr) (referred to as NH-NU), is developed to integrate the advantages of semiconductor photocatalysts and porous CO(2) adsorbents for CO(2)-to-CH(4) conversion. The NH-NU Z-scheme heterojunctions are fabricated via a simple one-pot solvothermal method, enabling the formation of a tight and uniform interface between the two phases, thereby facilitating the separation and transfer of the photoinduced charge carriers, as confirmed by TEM, EPR, electrochemical studies, and work functions. As a result, the as-prepared photocatalyst demonstrates a significant increase in selectivity for CH(4) production through CO(2) photoreduction, achieving a 10-fold enhancement compared to that of the pristine MOF, NH(2)-UiO-66. Moreover, there is no obvious decrease in the photocatalytic activity for CH(4) production across four consecutive cycles. In situ FT-IR spectroscopy and DFT calculations reveal that charge-enriched N-doped NH-NU-3 composites stabilize various C(1) intermediates in multistep elementary reactions, leading to superior selectivity in the CO(2)-to-CH(4) conversion process. This work establishes that efficient and selective heterogeneous catalytic processes can be achieved through the stabilization of reaction intermediates by designing suitable Z-scheme heterojunctions.